Increasing frequency of hydrologic extremes under changing climate warrants a revisit to the design practices considering non-stationarity to safeguard the hydro-systems. This study proposes a novel method integrating wavelet based selection of dominant climatic oscillations with extreme value formulations for developing non-stationary frequency relations of rainfall, temperature and streamflow of Greater Pamba river basin in Kerala, India, which successfully captured the extremes of 2018.